In the Ozarks, the river keeps its dead—and its secrets bite back. When a kayak tour shoots into a cave beneath Missouri’s Mark Twain National Forest, the lead guide strikes a chain stretched across the darkness. In the churn that follows, a bloated body surfaces—weighted, toothless, and staged like a warning. FBI analyst Wren Cade is flown in with partner Eli Barron and trainee-agent Tiffany Brooks, only to find the caves doubling as cartel arteries and a backwoods revival movement preaching from boats at dusk. A century-old pamphlet by a fire-and-brimstone preacher— Practicing Presence —starts showing up at scenes. Each chapter foreshadows a fresh ritual: teeth pulled, weights tied, mouths stopped. Is a believer killing by doctrine, or is a golden-toothed enforcer using the myth to hide executions in plain sight? As Wren traces a lattice of underground rivers, meth labs, and borrowed faith, she’s pulled between a missing-person crisis in her own family and a town ready to call murder a miracle. Chain in the Dark is Book 7 in the Wren Cade series—propulsive, atmospheric, and emotionally sharp.